with the snowfall that it incorporated within it. one could liken glaciers as adepositionalenvironment, aglacial environment. in the deposits are contained events of earth history that occur simultaneously during the depositional process. you see, ice sheets are essentially atmospheric processes. practically any material passing through the atmosphere may be trapped in glaciers as they form. pollen, volcanic ash, and meteorites have been discovered in the ice. even bubbles of ancient air have been found, representing a valuable record of earth's past atmosphere and climate. since the early 1970s, an international project has been underway to drill into greenland's vast continental glacier and obtain ice core samples. called the greenland ice core program, this effort involves scientists from countries around the world. the prime difficulties in a field operation such as drilling in ice relate primarily to the climate, the weather. it's not the best place to work, but it's overcome somewhat by the technique used today to excavate trenches and cover the tops of the trenches over with some form of

intoanenvironmentofheavy balls or light balls? heavy balls. and you want the thing to slow down. let me ask you this. if i take a ball and i throw it against a brick wall-- [makes sounds] --when it bounces off, will it bounce off a lot slower or about the same? about the same. about the same. if i take a golf ball and i throw it against a bowling ball, is that bowling ball gonna slow the golf ball down? no, it's not. so what you do is you take the golf ball and you throw into an arena of ping-pong balls. and if you do that, it will give what? give the energy to ping-pong ball and it itself will slow down. and so what do you do is you take these things and you bounce them off atoms like the size of carbon. did you ever hear about the heavy water? you bounce them off light atoms or molecules and these things will slow down, so they're moderated and will cause the reaction of more of this fission. you call--nuclear fission, gang, breaking apart, nuclear fission, and you will fission more atoms. anyway, this is something that cause an awful lot of excitement. because along with these two, it turns